Six years ago, the devastating Tohoku earthquake and tsunami struck the coast of Japan. Since then, it has become evident that hundreds of coastal species from Japan have crossed the Pacific Ocean on tsunami debris, including species that have become invasive and been known to cause ecosystem/economic damage elsewhere. As of January 2017, scientists have documented the arrival of >650 debris items, referred to as Japanese Tsunami Marine Debris Biofouling Items (JTMD-BF) 1-651. Debris items include docks, buoys, boats, pallets, and wooden structures. These items were identified as JTMD if it 1) had clear identification such as a serial or registration number that was linked to an object lost during the tsunami of 2011; 2) had clear biological evidence of originating primarily from the Tohoku coast of Japan; or 3) a combination of these factors. The BF items are a subset of all the debris lost, as some debris items that were known to be lost from Japan remain undocumented – it is possible they ended up in remote locations. A huge effort by taxonomists to identify the species on JTMD has generated a comprehensive species list. Currently, there are around 300 taxa that have been collected on JTMD from North American and Hawai`ian coastlines since 2012. I am interested in looking at several spatial aspects of the dataset as research questions. First of all, I want to explore the geographic distributions of the species with invasion history compared to those without invasion history. I also want to look at a few species of interest, and map their geographic distributions to compare (both native and non-native on the same map). Lastly, I want to explore the different methods of transport, or vectors, that have been documented for 31 of the JTMD species, to better understand different dispersal mechanisms and patterns.

Dataset: JTMD Database

My work is part of an international effort to evaluate the risks associated with JTMD and associated species. I contributed to the development of a database of life history, distributional, and environmental attributes of many JTMD species. This database is being used for reference and analysis, and can aid in efforts to assess the risk associated with JTMD species, and in determining which species are of highest concern for establishment in certain areas. The database contains a little over 100 JTMD species, with 26 attributes per species. It has information for native geographic regions and non-native (if applicable) geographic regions, as well as vector information, meaning the methods of transport that species have used to disperse to different regions of the world. The regions are classified as the Marine Ecoregions of the World. It also has survival temperature and salinity regimes, reproductive information, habitat, depth, trophic level, abundance data, and more. The database does not include temporal information, but these species arrived on debris items in pulses for years after the tsunami event, and that is another interesting aspect of the phenomenon.

Hypotheses: While the JTMD species are largely native to the Northwest Pacific (near Japan), they are also native to regions from all over the world. I hypothesize that most species without invasion history are native to the NW Pacific, and those with invasion history are native to regions all over the world. I expect to see this represented when their native regions are mapped. For the species that have been found outside their native range, I expect to see that some are only just outside native ranges in a few areas, but some with a history of invasion are more globally distributed.

For the individual maps of species of interest, I am not sure how they will compare, but I expect some to be more global, and some to be more localized, and only invasive in one realm.

For the vector types, I expect to see a lot of overlap of geographic regions between different types of vectors, because there is a lot of overlap in documentation. What I mean by overlap is that most species that were introduced to a certain region via ballast water were also introduced via aquaculture/fisheries trade, for example, and that can result in similar looking maps for different vector types.

The following map shows the total number of JTMD species native to each region, with a legend on the side specifying what range each color represents.

Results: The most prevalent region that JTMD species are native to is the Temperate Northern Pacific. This seems obvious, as JTMD originated from Japan, so we expect most species to be native to that same region of the globe. Next most prevalent native region for JTMD species is Eastern Indo-Pacific, the region southeast of Japan. However, after that the native regions that are prevalent for JTMD species begin to span the globe: Temperate Northern Atlantic, and Tropical Eastern Pacific. At the other end is the least prevalent region: the Southern Ocean, only one JTMD species is native to this cold southern region.

Looking at Individual Species geographic ranges

What are the geographic distributions of some of the ‘riskier’ species that arrived on Japanese Tsunami Marine Debris (JTMD)? What do their native and non-native ranges look like, and how do they compare with each other?

First of all, I had to choose 4 species with clear invasion history out of the 104 JTMD species, to focus on. Out of the 31 with invasion history, I chose Asterias amurensis (seastar) and Hemigrapsus sanguineus (Japanese shore crab) since they are known to be an issue in other regions. I then chose two species with large non-native spread: Crassostrea gigas (Japanese oyster), an economically important aquaculture species, and Teredo navalis, the shipworm with an almost global distribution that has burrowed in wooden ships all over the globe for 100’s of years.

The approach I used was within ArcMap. I manipulated the Layer Properties in ArcGIS ArcMap 10.4.1 in order to manipulate the polygons in the shape file, to make them appear different colors according to which realms were documented as native or non-native regions for each species.

Crassostrea gigas geographic distribution

Teredo navalis geographic distribution

JTMD species vector distribution:

The maps below show the number of species that were introduced to each realm via each vector type. As you can see by looking at the first map for natural dispersal, the most prevalent regions are Temperate Northern Atlantic, and Temperate Northern Pacific. For the second map of moveable structures, the most prevalent regions are Temperate Northern Pacific, and Southern Australia/ New Zealand.

For solid ballast, the most prevalent region for this vector is Southern Australia/ New Zealand. For recreation, the most prevalent regions are Temperate Northern Atlantic, along with Southern Australia/ New Zealand.

For the method of transport of ballast water, the most prevalent regions are Temperate Northern Pacific, Temperate Northern Atlantic, along with Southern Australia/ New Zealand, and Southern Africa. For aquaculture and fisheries trade, the most prevalent regions are Temperate Northern Pacific, Temperate Northern Atlantic, along with Southern Australia/ New Zealand.

Approaches: The approach I used was within ArcMap. I chose to visually represent native region frequency of JTMD species within 12 different coastal geographic regions of the world. For the second part of individual species maps, I manipulated the Layer Properties in ArcGIS ArcMap 10.4.1 in order to manipulate the polygons in the shape file, to make them appear different colors according to which realms were documented as native or non-native regions for each species. For the last part of my project, I visually represented vector distribution frequency of JTMD species within 12 different coastal geographic regions of the world, with a different map for each vector type.

Significance: Human-mediated transport of marine species across the globe through ballast water and hull fouling has been a concern for some time. JTMD is unique in comparison to these marine vectors, in that it can transport large numbers of marine species across ocean basins. Shipping routes are direct and arrive in known locations and at measurable frequencies whereas JTMD, which is propelled by winds and currents and travels at much slower speeds than ships, can arrive almost anywhere at any time. JTMD is potentially the transport vector with the most random distribution yet described. Due to the slow rates of transport by currents rather than propulsion, the effects of drag and dislodgement are reduced on JTMD in comparison with ship hull Furthermore, JTMD transports large numbers of adults, rather than larval stages that are more common in ballast water. As of January 2017, only one JTMD species, the striped beakfish Oplegnathus fasciatus, has been observed free-living in along the west coast of North America (in Oregon and Washington). At this time, we do not know if any of these JTMD species will become established outside of their current distributional range as a result of the earthquake and tsunami. But by studying the JTMD species invasion histories, and geographic distributions of both native and non-native areas, we can better understand this large dispersal event, and inform vector management response for future events.

The maps that were created during this class are useful for my research, and are really nice ways to visualize the native regions of the JTMD species, the distribution of the JTMD species, and the vector distribution of the JTMD species. I can potentially use these maps for reports and thesis work on JTMD species in the future.

My Learning: I started out the class as a beginner in spatial analysis, and with no experience in GIS, or Arc-Info. Being a beginner, I had to do a lot of self-exploration, tutorial watching, and asking for help from peers and teachers. I am happy to report that I gained a lot of comfort using ArcMap, and can now get a shape file into ArcMap, get data as another layer over the shape file, and join data, manipulate the layer properties, and create maps with legends in ArcMap. I am happy with these skills, and I feel that I learned a lot about beginner ArcMap usage, and feel more comfortable talking about GIS mapping with others now.

Statistical knowledge: I didn’t use statistical analysis with my project, as my data was for very large realms of the marine regions of the ocean, and didn’t lend itself to statistical analysis, so I did exploratory analysis and visualizing as means of analysis. However, by talking to others in the class, and learning about what their methods were, I learned some new methods for spatial analysis, like variograms, that I can potentially use in the future.

Comments: I got very intuitive comments from students on my tutorials. One suggestion was to look at frequency of occurrence for each debris item, and map that, which I wasn’t able to incorporate because I don’t have the necessary data, but it was a good suggestion if we did have it. I also used the comments from Julia on my exercises to guide my exploration for future exercises. For example one of Julia’s suggestions was to map the number of species introduced to each region by a vector, and that is exactly what I ended up doing to visualize the vector distribution of JTMD species.